The present invention relates to the field of the motorcycles industry and more precisely it relates to an actuator device for operating the stand of motorcycles.
In particular, the invention relates to an automatically releasable hydraulic valve, used, but not exclusively, for operating motorcycles stands.
In motorcycles and in scooters the manoeuvre of bringing the vehicle supported by the stand requires always a relevant physical force and is often troublesome. Such troubles arise the more the size and the weight of the scooter increase, and are highest with big motorcycles, whose weight without driver is even about 400 Kg. For people of small build and for some women this manoeuvre becomes in some cases impossible.
Attempts have been made in the past for actuating the stand of motorcycles by electromechanical systems. Parts mountable on existing motorcycles are known, even if not used frequently, which have, however, the drawback of being too complicated and expensive, and in which the safety problems have not been overcome sufficiently. In particular, such systems do not allow satisfactorily the release of the drive mechanism for allowing the stand to be used traditionally in case of failure of the system or in case of wrong manoeuvre by the user.
Object of the present invention is to provide a device for actuating the stand of motorcycles that can be operated electrohydraulically.
It is another object of the present invention to provide a single-acting actuator device, that operates the stand in a way that the motorcycle can be released from the stand traditionally.
It is a particular object of the invention to provide an actuator device for a motorcycle stand that has not the drawback of the known electromechanical actuators and comprises in a single unit all the functions necessary for operating the stand, as well as provides maximum safety, simple operation by the driver, stiffness, low encumbrance and easy installation on the vehicle.
It is a further object of the invention to provide a special hydraulic valve which automatically returns to a rest position as soon as the oil flow is stopped.
These and other objects are achieved by the actuator device and by the valve according to the present invention.
According to a first aspect of the invention, a device for actuating the rotation of a stand of a motorcycle, wherein the stand is pivotally connected to the motorcycle and are provided means for resiliently returning it from a standing position to a rest position, comprises at least an hydraulic actuator operating an actuating member between a first and a second position. The actuating member, when passing from the first to the second position, engages with the stand up to bringing it respectively from the rest position to the standing position. A flow control hydraulic circuit is provided that delivers liquid under pressure to the actuator for moving the actuating member from the first to the second position and allows the return stroke of the actuating member in the first position when the flow of the liquid ceases, whereby the stand can be turned to the rest position independently from the actuating member.
Advantageously, the flow control hydraulic circuit comprises a flow control valve connected with a first and a second opening of passage of liquid of the hydraulic actuator. The flow control valve comprises:
a cylinder,
a piston that slides in the cylinder and divides it into a first and a second chamber,
an inlet mouth of liquid under pressure into the first chamber, connected with the delivery of a pump suitable for supplying pressurised liquid,
an outlet mouth of liquid from the second chamber connected with the suction duct of the pump,
the second chamber having a delivery mouth connected with the first opening of the actuator,
the piston has axial through holes for connecting the first and second chamber;
resilient means are provided that bias the movement of the piston to reduce the second chamber by means of the liquid flow through the holes;
the outlet mouth communicates also with the second opening of the actuator;
stopping means of the outlet mouth are provided according to the movement of the piston for reducing the second chamber, whereby the liquid flowing through the holes stops the outlet mouth causing the passage of liquid through the delivery mouth.
Preferably, the stopping means of the outlet mouth comprise a needle that extends from the piston through the second chamber. The hydraulic actuator may be an hydraulic cylinder and the actuating member may be a stem that moves between an extended position and a retracted position, the stem being in the retracted position when it is located in the second position. Alternatively the stem is in the retracted position when it is located in the first position.
In a preferred embodiment, the means for allowing the back stroke of the stem in the extended position comprises a pivot with a transversal hole and rotatably connected to the stand, the stem slidingly engaging with the hole and having an enlarged end with respect to the hole, whereby the passage of the stem from the extended position to the retracted position causes the pulling of the pivot and then the pulling of the stand from the rest position to the standing position.
The hydraulic cylinder may comprise a first and a second opening of passage of liquid for operating the movement of the stem between the extended position and the retracted position, resilient means being provided for pushing the stem to the extended position and pushing the liquid out through the first opening.
In an alternate embodiment, the actuator for moving the actuating member from the first to the second position allows the return stroke of the actuating member and the stand, the stand being pivotally connected to the actuating member whereby the actuating member returns to the extended position only when the stand returns to the rest position.
According to another aspect of the invention, an hydraulic valve associated to an hydraulic actuator is provided as above described.